FIG. 10 shows multiple mediate members 93, such as bearings, are mounted to a spindle 91 which is rotatably connected to a fixed frame 92 by the mediate members 93. The spindle 91 is the high speed spindle installed to a machine and a locking member 94 is locked on the distal end of the spindle 91 so that the mediate members 93 are prevented from dropping from the spindle 91. The locking member 94 can be a precision nut.
The locking member 94 is locked on the spindle 91 by using a wrench which outputs a pre-set torque so that the locking member 94 is properly locked on the spindle 91 and presses the mediate members 93 which are located between the spindle 91 and the fixed frame 92. When the spindle 91 rotates at high speed relative to the fixed frame 92, the force applied to the mediate members 93 is the axial force which is the force applied on the axis of the spindle 91.
There is a pre-set value for the axial force applied to the mediate members 93. The value is larger along with the larger size of the diameter or width of the mediate members. The manufacturers prepares a testing device to which the spindle 91 and the fixed frame 92 are installed, when the locking member 94 starts to be locked, the testing device shows the torque of the locking member 94 and when the torque applied to the locking member 94 reaches the pre-set value, the mediate members 93 are supposed reach the pre-set axial force. The manufacturers are acknowledged the axial force applied to the mediate members 93 by checking the torque output from the wrench.
However, the spindle 91 installed on the testing device cannot performs exactly the same as the spindle 91 on a machine, generally, the performance of the spindle on the testing device is better than that on the real machine, the required torques of the two different situations are different.
The cost for manufacturing the testing device which is a customer made device is high, and the testing device requires routine maintenance which increases the economic burden of the manufacturers.
The fixed frame 92 is specially manufactured so as to be cooperated with the testing device, and the fixed frame 92 will be smaller than the frame on the machine, so that the test result will be varied.
The present invention intends to provide an axial force testing device which improves the shortcomings of the conventional testing device.